Light emitting diode panel and method for manufacturing the light emitting diode panel

ABSTRACT

A light emitting diode (LED) panel is provided. The LED panel includes a thin-film transistor (TFT) backplane which includes an insulator film disposed on a top surface of a substrate, a plurality of organic films disposed on a top surface of the insulator film, and pixel electrodes disposed on a top surface of each of the plurality of organic films. The LED panel further includes a plurality of LEDs respectively bonded to the pixel electrodes disposed on the top surface of each of the plurality of organic films, wherein the plurality of organic films has the different heights according to a type of each of the plurality of LEDs respectively bonded to the pixel electrodes disposed on the top surface of each of the plurality of organic films.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This application is a continuation application of U.S application Ser.No. 16/251,816, filed Jan. 18, 2019, which is based on and claimspriority under 35 U.S.C. § 119(a) to Korean Patent Application No.10-2018-0010895, filed on Jan. 29, 2018, in the Korean IntellectualProperty Office, the disclosures of which are incorporated by referenceherein in their entirety.

BACKGROUND 1. Field

The disclosure relates to a display panel and a method for manufacturingsame. More particularly, the disclosure relates to a light emittingdiode (LED) panel and a method for manufacturing same.

2. Description of Related Art

Unlike liquid crystal display (LCD) panels, which display an image usinga backlight and an LCD, LED panels illuminate LEDs and directly displayan image without the need for a backlight layer or a liquid crystallayer. LED panels may use three LEDs respectively including a red (R)LED, a green (G) LED, and a blue (B) LED to constitute each pixel.

LED panels may be manufactured by bonding the respective R, G and B LEDsto a thin-film transistor (TFT) backplane for each type by a stamper. Inthis case, the respective R, G, and B LEDs are manufactured in differentways and have different thicknesses, whereas areas to which therespective LEDs are bonded on the related-art TFT backplane are formedto have the same height, which may be a problem.

For example, if the R LED is thinner than the G LED and the B LED, therelatively thin R LED may be easily broken into pieces as compared withthe Green and B LEDs. If the R LED is bonded first (to the TFTbackplane) and then, the G and B LEDs are bonded, the relatively thin RLED may receive interference of the stamper, etc. in the subsequentprocess (that is, process of bonding G and B LEDs), thus increasing thechances that the R LED will be broken. In addition, if the R LED isbonded the last to eliminate interference from the subsequent process,the R LED may be unbonded, and if a pressure of the stamper is increasedtoo much to bond the R LED, the R LED may be broken into pieces.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Provided are a light emitting diode (LED) panel which is formed suchthat LED bonding areas on the TFT backplane have different stepsaccording to LED types, and a method for manufacturing the LED panel.

According to embodiments, a light emitting diode (LED) panel isprovided. The LED panel includes a thin-film transistor (TFT) backplaneincluding: an insulator film disposed on a top surface of a substrate; aplurality of organic films disposed on a top surface of the insulatorfilm, the plurality of organic films having different heights from thetop surface of the insulator film, each of the plurality of organicfilms being one among a transparent organic film, an opaque organicfilm, and a polymide; and pixel electrodes disposed on a top surface ofeach of the plurality of organic films. The LED panel further includes aplurality of LEDs respectively bonded to the pixel electrodes disposedon the top surface of each of the plurality of organic films, whereinthe plurality of organic films has the different heights according to atype of each of the plurality of LEDs respectively bonded to the pixelelectrodes disposed on the top surface of each of the plurality oforganic films, wherein a thinnest LED among the plurality of LEDs isbonded to the pixel electrodes disposed on the top surface of organicfilm having a lowest height among the plurality of organic films,wherein an additional organic film is formed on an area between thepixel electrodes disposed on the top surface of each of the plurality oforganic films, the additional organic film having a predetermined heightfrom the top surface of each of the plurality of organic films, whereinthe plurality of LEDs includes a first type LED, a second type LED, anda third type LED, and wherein the first type LED is thinner than eitherone or both of the second type LED and the third type LED.

According to one or more embodiments, the plurality of LEDs respectivelycorresponds to a plurality of sub pixels included in one pixel.

According to one or more embodiments, the plurality of organic films isa black matrix.

According to one or more embodiments, the one organic film is disposedat a predetermined height between the pixel electrodes disposed on theone organic film.

According to embodiments, a light emitting diode (LED) panel isprovided. The LED panel includes a thin-film transistor (TFT) backplaneincluding: an insulator film disposed on a top surface of a substrate; aplurality of organic films disposed on a top surface of the insulatorfilm, the plurality of organic films having different heights from a topsurface of the insulator film, each of the plurality of organic filmsbeing one among a transparent organic film, an opaque organic film, anda polymide; and pixel electrodes disposed on a top surface of each ofthe plurality of organic films. The LED panel further includes aplurality of LEDs respectively bonded to the pixel electrodes disposedon the top surface of each of the plurality of organic films, whereinthe plurality of organic films has the different heights according to atype of each of the plurality of LEDs respectively bonded to the pixelelectrodes disposed on the top surface of each of the plurality oforganic films, wherein a thinnest LED among the plurality of LEDs isbonded to the pixel electrodes disposed on the top surface of organicfilm having a lowest height among the plurality of organic films,wherein an additional organic film is formed on an area between thepixel electrodes disposed on the top surface of each of the plurality oforganic films, the additional organic film having a predetermined heightfrom the top surface of each of the plurality of organic films, whereinthe plurality of LEDs includes a first type LED, a second type LED, anda third type LED, and wherein the first type LED has a smallestthickness among the plurality of LEDs.

According to one or more embodiments, one LED having a smallestthickness among the plurality of LEDs is bonded to the pixel electrodesdisposed on the top surface of one organic film having a smallest heightamong the plurality of organic films.

According to one or more embodiments, one among the plurality of organicfilms is disposed at a predetermined height between the pixel electrodesdisposed on the one among the plurality of organic films.

According to various embodiments, problems of LED unbonding or LED crackthat may occur due to a difference of thickness according to LED typesin the process of bonding the LED to the TFT backplane can be minimized.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram illustrating a pixel structure of a TFT backplane,according to an embodiment;

FIG. 2 is a diagram illustrating an LED bonding area on one sub pixelarea included in the TFT backplane, according to an embodiment;

FIG. 3A is a diagram illustrating problems with a related art;

FIG. 3B is a diagram illustrating problems with a related art;

FIG. 3C is a diagram illustrating problems with a related art;

FIG. 4A is a diagram illustrating a method for manufacturing an LEDpanel, according to various embodiments;

FIG. 4B is a diagram illustrating a method for manufacturing an LEDpanel, according to various embodiments;

FIG. 5A is a diagram illustrating a method for manufacturing a TFTbackplane, according to various embodiments;

FIG. 5B is a diagram illustrating a method for manufacturing a TFTbackplane, according to various embodiments;

FIG. 5C is a diagram illustrating a method for manufacturing a TFTbackplane, according to various embodiments;

FIG. 5D is a diagram illustrating a method for manufacturing a TFTbackplane, according to various embodiments;

FIG. 6A is a diagram illustrating an embodiment for preventing ashort-circuit of anode and cathode terminals when an LED is bonded tothe TFT backplane;

FIG. 6B is a diagram illustrating an embodiment for preventing ashort-circuit of anode and cathode terminals when an LED is bonded tothe TFT backplane;

FIG. 6C is a diagram illustrating an embodiment for preventing ashort-circuit of anode and cathode terminals when an LED is bonded tothe TFT backplane; and

FIG. 7 is a diagram illustrating a TFT backplane, according to anotherembodiment.

DETAILED DESCRIPTION

Specific embodiments are illustrated in the drawings and are describedin detail in the detailed description. However, it is to be understoodthat the disclosure is not limited to a specific embodiment, butincludes all modifications, equivalents, and substitutions withoutdeparting from the scope and spirit of the disclosure. In relation toexplanation of the drawings, same or similar drawing reference numeralsmay be used for similar constituent elements.

Further, when it is mentioned that one element (e.g., first element) isoperatively or communicatively coupled with or connected to anotherelement (e.g., second element), it may be understood as including allthe examples where each of the elements is directly coupled orindirectly coupled via yet another element (e.g., third element).When itis mentioned that one element (e.g., first element) is “directlycoupled” with or “directly connected to” another element (e.g., secondelement), it may be understood that there is no element (e.g., thirdelement) present between the element and the other element.

Herein, expressions such as “at least one of” when preceding a list ofelements, modify the entire list of elements and do not modify theindividual elements of the list. For example, the expression, “at leastone of a, b, and c,” should be understood as including only a, only b,only c, both a and b, both a and c, both b and c, or all of a, b, and c.

The terms used in various embodiments of the disclosure are just for thepurpose of describing particular embodiments and are not intended tolimit the disclosure. In addition, the singular expression does notlimit the disclosure to have a single component or step. Instead, thedisclosure may comprise multiple components or steps even if describedin singular expression.

All of the terms used herein including technical or scientific termshave the same meanings as those generally understood by a person ofordinary skill in the related art unless they are defined otherwise. Theterms defined in a generally used dictionary should be interpreted ashaving the same meanings as the contextual meanings of the relevanttechnology and should not be interpreted as having ideal or exaggeratedmeanings unless they are clearly defined in the various embodiments.According to circumstances, even the terms defined in the embodimentsshould not be interpreted as excluding the embodiments of thedisclosure.

Hereinafter, various embodiments of the disclosure will be described indetail with reference to the accompanying drawings.

FIG. 1 is a diagram illustrating a pixel structure of a thin-filmtransistor (TFT) backplane 100, according to an embodiment. Asillustrated in FIG. 1, the TFT backplane 100 may have a structure inwhich a plurality of sub pixel areas 110-1, 110-2 and 110-3 defined bygate lines G1, G2, Gn and data lines D1, D2, Dn are arranged in acheckerboard form.

Here, the number of the plurality of sub pixel areas 110-1, 110-2 and110-3 included in a single pixel area 110 is the same as the number ofsub pixels per pixel (three in the example of FIG. 1). For example, theplurality of sub pixel areas 110-1, 110-2, and 110-3 may correspond toan R sub pixel, a G sub pixel, and a B sub pixel, respectively. In thiscase, an R LED, a G LED, and a B LED may be respectively bonded to thesub pixel areas 110-1, 110-2, and 110-3 and included in one pixel (orunit pixel) of the LED panel.

For example, the sub pixel area 110-1 may include at least onetransistor 111 and two pixel electrodes 112 and 113. In FIG. 1, the twopixel electrodes 112 and 113 are implemented as a power electrode 112and a common electrode 113, and one transistor 111 is provided only onthe power electrode 112 side. However, according to embodiments, the twopixel electrodes may be respectively implemented as a power electrodeand the two transistors may be provided on the respective sides of thetwo power electrodes. The remaining sub pixel areas 110-2 and 110-3 maybe similarly arranged.

On the two pixel electrodes 112 and 113, the corresponding LED may bebonded and one sub pixel of the LED panel may be formed. Here, an areato which the LED is bonded on the TFT backplane 100 may be referred toas an LED bonding area. In this case, the TFT backplane 100 may be astructure in which a power is supplied to at least one of the two pixelelectrodes 112 and 113 and the bonded LED emits light.

FIG. 2 illustrates an LED bonding area 200 on one sub pixel area 110-1included in the TFT backplane 100. For example, one LED from among theR, G, and B LEDs may be bonded to the LED bonding area 200 to constituteone sub pixel of the LED panel.

The remaining sub pixel areas 110-2 and 110-3 may respectively includethe LED bonding area as illustrated in FIG. 2 as well. Accordingly, theR, G and B LEDs may be respectively bonded to the LED bonding areas ofthe sub pixel areas 110-1, 110-2, and 110-3 to constitute one pixel ofthe LED panel.

As described above, the R, G, and B LEDs may be respectivelymanufactured in different ways, and thus the thicknesses thereof may bedifferent. Accordingly, in a case that the LED bonding areas formed onthe TFT backplane all have the same height, a problem in which the LEDis unbonded or broken in the LED bonding process may occur.

According to an embodiment, the LED bonding areas included in the TFTbackplane 100 may be formed on the TFT backplane 100 to have differentheights according to types of LED to be bonded. In addition, arelatively thin LED may be bonded to an LED bonding area of a relativelylow height from among the LED bonding areas to constitute an LED panel.By manufactured an LED panel this way, problems occurring in the LEDbonding process according to the related art may be overcome.

The problems of the related art will be described in greater detailbelow with reference to FIGS. 3A, 3B, and 3C, and an LED panelmanufacturing process according to an embodiment will be described withreference to FIGS. 4A and 4B.

FIGS. 3A, 3B, and 3C are diagrams illustrating problems with a relatedart. FIG. 3A is a cross-sectional view of one pixel area included in arelated-art TFT backplane 300.

As illustrated in FIG. 3A, one pixel area of the related-art backplane300 may include three sub pixel areas 310, 320, and 330. The first subpixel area 310 may include a transistor 311 and two pixel electrodes 312and 313. The second sub pixel area 320 may include a transistor 321 andtwo pixel electrodes 322 and 323. The third sub pixel area 330 mayinclude a transistor 331 and two pixel electrodes 332 and 333.

Here, the sub pixel areas 310, 320, and 330 may respectively include LEDbonding areas 300-1, 300-2 and 300-3 to which an LED is bonded. Asillustrated the respective LED bonding areas 300-1, 300-2, and 300-3 ofthe related-art TFT backplane 300 are formed at a uniform heightregardless of types of LED to be bonded.

FIG. 3B illustrates a process of manufacturing an LED panel by bondingan LED onto the related-art TFT backplane 300. The LED panel may bemanufactured by sequentially bonding an LED to the LED bonding areas300-1 to 300-3 on the TFT backplane 300 using a stamper 50. In thiscase, the respective LEDs 10, 20, and 30 may be bonded onto therespective pixel electrodes 312/313, 322/323, and 332/333 in the LEDbonding areas 300-1 to 300-3 through a metal bump 60 which is aconductive melting material.

As described above, a difference of thickness may be present among LEDsby type and thus, in a case that an LED is bonded to the LED bondingareas 300-1 to 300-3 of the related-art TFT backplane 300 of the sameheight, a problem may occur in the bonding process.

Referring to FIG. 3B, the R LED 10 is thinner than the G LED 20 and theB LED 30. This is due to a difference of LED epitaxial growth. Forexample, in a case that the R LED 20 uses gallium arsenide (GaAs) toproceed with the LED epitaxial growth process and that the G and B LEDs20 and 30 use gallium nitride (GaN) to proceed with the LED epitaxialgrowth process, an ultimate thickness of the R LED 10 may be thin ascompared with thicknesses of the G and B LEDs 20 and 30 as illustratedin FIG. 3B.

When bonding the respective R, G, and B LEDs to the TFT backplane 300, abonding pressure of the stamper 50 remains unchanged and thus, in a casethat the relatively thick G and B LEDs 20 and 30 are bonded first andthen, the R LED 10 is bonded at the same bonding pressure, a problemthat the relatively thin R LED 10 is unbonded may occur.

FIG. 3C illustrates a problem that may occur when a bonding pressure ofa stamper is increased to resolve the unbonding problem of the R LED 10as in FIG. 3B. The R LED 10 is fragile because it is thin and has weakproperties. Accordingly, in a case that a stamper pressure is increasedto bond the R LED 10, a crack may occur in the R LED 10 as illustratedin FIG. 3C. Although it is possible to set an appropriate stamperpressure at which the R LED 100 is bonded without cracking, it is noteasy to find the appropriate stamper pressure, and even if the pressureis changed only slightly, an unbonding or cracking of the R LED mayoccur.

In order to try and solve these problems, boning the R LED 10 first andthen, bounding the G and B LEDs 20 and 30 has been considered in therelated art. However, this may increase the chances that the bonded RLED 10 will be interrupted in the subsequent process, that is, theprocess of bonding the G LED 20 and the B LED 30, which is notdesirable.

In contrast, according to an embodiment, the LED bonding area of the TFTbackplane may be formed at different heights according to a type of anLED to be bonded, and the relatively thin LED may be bonded to the LEDbonding area at a relatively low height to manufacture an LED panel, andthereby the problem described above may be overcome.

FIGS. 4A and 4B are diagrams illustrating a method for manufacturing anLED panel, according to various embodiments.

FIG. 4A is a cross-sectional view of one pixel area included in the TFTbackplane, according to an embodiment. As illustrated in FIG. 4A, onepixel area of the TFT backplane 400 according to an embodiment mayinclude three sub pixel areas 410, 420, and 430, and the respective subpixel areas 410, 420, and 430 may include one transistor 411, 421, and431 and two pixel electrodes 412/413, 422/423, and 432/433. In thiscase, the respective pixel electrodes may include an anode electrode412, 422 and 432, and a cathode electrode 413, 423, and 433.

In the TFT backplane 400 according to an embodiment, the LED bondingheights 400-1, 400-2, and 400-3 may be formed at different heightsunlike the related-art TFT backplane 300 of FIG. 3A. For example, theLED bonding area 400-1 may be formed at the lowest level, the LEDbonding area 400-2 may be formed at the intermediate level, and the LEDbonding area 400-3 may be formed at the highest level among the bondingareas.

However, embodiments are not limited to any specific examples. That is,when it is assumed that heights of the LED bonding areas 400-1, 400-2,and 400-3 on the TFT backplane 400 are respectively represented as A, B,and C, it may be formed as shown in A<B<C as illustrated in FIG. 4A, butmay be, in an implementation, as shown in A<B=C,A=B>C,orA>B>C.

FIG. 4B illustrates a process of manufacturing an LED panel by bondingR, G, and B LEDs onto the LED bonding areas 400-1 to 400-3 of the TFTbackplane.

For example, according to an embodiment, a relatively thin LED fromamong a plurality of LEDs may be bonded to an LED bonding area of arelatively low level from among the plurality of LED bonding areas.

For example, while thicknesses of the R, G, and B LEDs 10, 20, and 30are represented as a, b, and c, respectively, when it is assumed thata<b=c , or that a<b<c, a relatively thin R LED 10 may, as illustrated insection (a) of FIG. 4B, may be bonded to the LED bonding area 400-1, andthe G LED 20 and the B LED 30 may be sequentially bonded to the LEDbonding areas 400-2 and 400-3, respectively, as illustrated in sections(b) and (c) of FIG. 4B.

In FIG. 4B, when it is assumed that the heights of the LED bonding areas400-1, 400-2, and 400-3 are represented as A, B, and C, respectively,the TFT backplane 400 is formed such that A<B<C as illustrated in FIG.4A, but is not limited thereto. For example, even in a case of a TFTbackplane in which the heights of the LED bonding areas 400-1 to 400-3have a relationship of A<B=C, as illustrated in FIG. 4B, the R, G, and BLEDs 10, 20, and 30 may be sequentially bonded to the corresponding LEDbonding area.

In a case of a TFT backplane on which the LED bonding areas 400-1 to400-3 have heights of a relationship of A=B>C, or A>B>C, unlike FIG. 4B,the relatively thinnest R LED 10 may be bonded to the LED bonding area400-3 of the relatively lowest level, and the G LED 20 and the B LED 30may be sequentially bonded to the LED bonding area 400-2 and the LEDbonding area 400-1, respectively.

According to the various embodiments, the LED bonding areas 400-1, 400-2and 400-3 included in the TFT backplane 400 may be formed at differentheights according to a type of LED to be bonded thereto, and arelatively thin LED may be bonded to an LED bonding area of a relativelylow height, thus eliminating the possibility of interference by thestamper 50 in the LED bonding process. Accordingly, an LED bondingdefect or an LED cracking problem by a stamper pressure can be resolved.

With regard to the planar view of the TFT backplane 400 illustrated inFIGS. 4A and 4B, the transistors 411, 421 and 431 are different inposition from those of FIG. 1, but this is only a difference in animplementation which is irrelevant to the gist of the disclosure.

In the example described above, the R, G, and B LEDs 10, 20 and 30 areincluded in one pixel, and when it is assumed that the thicknesses ofthe LEDs are represented as a, b, and c, respectively, the relationshipthereof are a<b=c or a<b<c. However, the example is not limited thereto.For example, one pixel of the LED panel may include three or more LEDs,and a relationship among the respective LEDs may differ depending on LEDmanufacturing processes.

That is, a type and the number of LEDs included in one pixel of an LEDpanel, and a relationship of thicknesses between LEDs may differaccording to embodiments. However, if a relatively thin LED is bonded tothe LED bonding area 400-1 of a relatively low level, the case may beincluded in the technical concept of the disclosure.

The description of other processes required for manufacturing an LEDpanel is omitted herein because they would obscure the gist of thedisclosure.

A method for manufacturing a TFT backplane according to an embodimentwill be described below. FIGS. 5A, 5B, 5C, 5D are diagrams sequentiallyillustrating a method for manufacturing a TFT backplane 500, accordingto various embodiments. FIGS. 5A, 5B, 5C, and 5D illustrate a process ofgenerating one pixel area including three sub pixel areas in the TFTbackplane 500.

A process of manufacturing the TFT backplane 500, which is also referredto as a TFT substrate, a TFT array, or a TFT panel, may first includeforming TFTs 511, 521, and 531 respectively corresponding to sub pixelsas illustrated in FIG. 5A, through a related-art TFT process.

For example, the respective TFTs 511, 521, and 531 may be manufacturedby a TFT process sequentially including forming gate electrodes 511-1,521-1 and 531-1 on the substrate 501, forming an insulator film 502 andsemiconductor films 511-2, 521-2, and 531-2 on the gate electrodes511-1, 521-1, and 531-1, and then forming source electrodes 511-3,521-3, and 531-3 and drain electrodes 511-4, 521-4, and 531-4.

In this case, the substrate 501 may be implemented as a glass. However,depending on circumstances, polyimide, polyethylene terephthalate (PET),etc. may be used. In addition, the semiconductor films 511-2, 521-2, and531-2 may be made of at least one material of amorphous silicon (a-Si),low-temperature poly silicon (LTPS), and oxide.

The gate electrodes 511-1, 521-1, and 531-1 formed on the substrate 501may function to control a current to flow or not to flow in thesemiconductor films 511-2, 521-2, and 531-2, and the insulator film 502may serve to separate the semiconductor films 511-2, 521-2 and 531-2. Inaddition, the source electrodes 511-3, 521-3, and 531-3 and the drainelectrodes 511-4, 521-4, and 531-4 may function as a data electrodewhich supplies and receives electrons through the semiconductor films511-2, 521-2, and 531-2.

The respective TFTs 511, 521, and 531 may serve as a sort of switchcontrolling a light emission intensity, light emission time, etc. of thecorresponding LED. FIG. 5A illustrates, by way of example, the TFThaving an inverted staggered structure, but the embodiment is notlimited thereto. As another example, the TFT having a staggeredstructure, a coplanar structure, an inverted coplanar structure, or thelike may also be used.

When the TFTs 511, 521, and 531 respectively corresponding to the subpixels are provided, as illustrated in FIG. 5B, an organic layer 550 maybe formed on the data electrodes (that is, the source electrodes 511-3,521-3, and 531-3) and the drain electrodes 511-4, 521-4, and 531-4.

For example, the organic film 550 may be evenly coated on the dataelectrodes. In general, a deposition process and a coating process maybe used to form an insulator film or an organic film layer. However,according to an embodiment, it is necessary that the LED bonding areasare formed at different heights as described above, and thus it isdesirable to form the organic film 550 through the coating processrather than through the deposition process.

A photosensitive material, that is, photo resist (PR), may be used forthe organic film 550. In this regard, a variety of acrylic materials maybe used for the organic film 550. For example, a transparent organicfilm (e.g., transparent organic layer material used in a manufacturingprocess of related-art LCD panels), an opaque organic film (e.g., blackmatrix), or Polyimide may be used.

The various embodiments relate to an LED panel directly displaying animage by illuminating an LED, and thus it is desirable to form an opaqueorganic film (black matrix) on a data electrode to prevent a lightemitted from an LED from being reflected off the TFT backplane 500. Thisis clearly different from forming a black matrix layer on a color filterin the LCD panel manufacturing process in terms of objective and effect.However, the example is not limited thereto, and depending oncircumstances, an organic film such as a transparent organic film andPolyimide may be used as well.

When a TFT substrate with which the organic film 550 is flat-coated isprovided, as illustrated in FIG. 5C, a light is radiated to the organicfilm 550 through a mask 570 having areas with different penetrationratios so that the LED bonding areas 552, 553, and 554 are formed atdifferent heights according to a type of LED to be bonded thereto.

As described above, a Photo Resist is used for the organic film 550, andthus, when a light is radiated to the organic film 550 through the mask570 having the areas 571 to 577 with different penetration ratios, anintensity of light radiated to the organic film 550 changes according topenetration ratios and thus, based on a penetration ratio of therespective parts 571 to 577, the corresponding organic film 550 may beformed at different heights.

FIG. 5C illustrates a case in which the organic film 550 is a negativePhoto Resist. The negative Photo Resist refers to a material which isremoved much during development as the radiated light is weak. FIG. 5Cillustrates a mask 570 that includes, for example, areas 571 and 574with a 100% penetration ratio, an area 573 with a 70% penetration ratio,an area 572 with a 50% penetration ratio, and areas 575, 576, and 577with a 0% penetration ratio.

Accordingly, when the light is radiated through the mask 570 anddeveloped, the organic film 550 may not be removed from the parts oforganic films 551 and 554 corresponding to the areas 571 and 574, may beremoved from the part of organic film 553 corresponding to the area 573,and further removed from the part of organic film 552 corresponding tothe area 572. In this sequence, the organic film is formed at agradually lower height. No light may be radiated to organic film partscorresponding to areas 575, 576, and 577, and thus it may be identifiedthat the entire organic film 550 is removed.

In FIG. 5C, the organic film 550 is a negative Photo Resist. However, apositive Photo Resist which is removed much during development as alight radiation increases may be used as an organic film.

As described above, a light is radiated through the mask 570 withdifferent penetration ratios and the organic films 552, 553, and 554 isformed at different heights for each LED bonding area, as illustrated inFIG. 5D, the pixel electrodes 512/513, 522/523, and 532/533 may berespectively formed on the organic films 552, 553, and 554 formed atdifferent heights, thereby manufacturing the TFT backplane 500 accordingto an embodiment. In this case, the respective pixel electrodes mayinclude an anode electrode 512, 522, and 532, and a cathode electrode513, 523, and 533.

FIGS. 6A, 6B, and 6C are diagrams illustrating an embodiment forpreventing anode and cathode terminals from being short-circuited whenan LED is bonded to the TFT backplane.

According to an embodiment, an LED bonding area of a TFT backplane mayfurther include an organic film of a predetermined height between twopixel electrodes (anode and cathode).

As described above, onto the two pixel electrodes, the corresponding LEDmay be bonded so that one sub pixel of an LED panel may be formed. Thatis, the anode/cathode terminals of the LED may be respectively bonded tothe anode/cathode terminals of the pixel electrode. However, in thiscase, the LED included in one sub pixel of the LED panel is very smallin size, and thus it is likely that a short-circuit will occur betweenthe anode terminal and the cathode terminal.

Accordingly, an organic film of a predetermined height may be formedbetween the anode terminal and the cathode terminal on the LED bondingarea, and thereby a short-circuit of the anode and cathode terminalsduring LED bonding can be prevented.

FIG. 6A illustrates a method for further forming an organic film of apredetermined height between two pixel electrodes included in therespective LED bonding areas. As described with reference to FIG. 5C, alight may be radiated to the organic film (photo resist) through a maskincluding areas with different penetration ratios, thereby forming anorganic film of different heights on the TFT backplane.

Accordingly, as illustrated in FIG. 6A, penetration ratios of the areas581, 582, and 583 of the mask 580 corresponding to an area betweenpositions at which the two pixel electrodes are to be formed on the TFTbackplane may be appropriately selected to thereby respectively form theorganic films 662, 663, and 664 further including the parts of organicfilm 662-1, 663-1, and 664-1 of predetermined heights between thepositions at which the two pixel electrodes are to be formed.

Thereafter, the pixel electrodes 612/613, 622/623, and 632/633 may berespectively formed on the organic film 662, 663, and 664 correspondingto the LED bonding area may be formed, and thereby, as illustrated inFIG. 6B, a TFT backplane 600 further including an organic film of apredetermined height between the two pixel electrodes 612/613, 622/623,and 632/633 may be manufactured.

In this case, as illustrated in FIG. 6B, even in a case that the LEDs10, 20 and 30 are respectively bonded to the pixel electrodes 612/613,622/623, and 632/633 through a metal bump 60 which is a conductivelymelting material, a short-circuit between the pixel electrodes 612/613,622/623, and 632/633 can be prevented.

In FIGS. 6A and 6B, an organic film of a predetermined height is furtherincluded in between two pixel electrodes included in the TFT backplanehaving LED bonding areas with different steps according to a type of LEDto be bonded thereto, but the example is not limited thereto. That is,as illustrated in FIG. 6C, an organic film of a predetermined height maybe formed between pixel electrodes included in a related-art TFTbackplane having LED bonding areas without steps, and thereby it ispossible to prevent a short-circuit between pixel electrodes that mayoccur during LED bonding.

In the example above, a case in which a TFT backplane includes anadditional pixel electrode is described. However, the technical conceptaccording to the various embodiments is not limited thereto. Forexample, the technical concept of the disclosure may be applicable to acase in which a TFT backplane 700 directly using a source/drain (SD)layer as a pixel electrode, that is, anode/cathode terminals, asillustrated in FIG. 7.

Even in a case in which the source/drain (SD) layer is directly used asanode/cathode terminals as illustrated in FIG. 7, the organic film 770may be coated on top of the SD layer and the light may be radiatedthrough a mask including areas with different penetration ratios, andthereby an organic film with different heights for each LED bonding areamay be formed. Accordingly, by forming an additional pixel electrode 712and 713 on the organic film of different heights, it is possible tomanufacture a TFT backplane with different heights according to a typeof LED to be bonded thereto. In FIG. 7, for convenience of explanation,only one sub pixel area is illustrated. However, an LED bonding areaincluded in surrounding another sub pixel area may be formed atdifferent heights from the organic film 770.

Hereinabove, an LED, an organic LED (OLED), a micro LED, etc. may bebonded to the LED bonding area, but the example is not limited thereto.

As described above, according to the various embodiments, problems ofLED unbonding or LED cracking that may occur due to a difference ofthickness according to LED types in the process of bonding the LED tothe TFT backplane can be minimized.

The foregoing embodiments and advantages are merely example and are notto be construed as limiting the disclosure. The present teaching can bereadily applied to other types of apparatuses. Also, the description ofthe embodiments is intended to be illustrative, and not to limit thescope of the claims, and many alternatives, modifications, andvariations will be apparent to persons having ordinary skill in the art.

What is claimed is:
 1. A light emitting diode (LED) panel comprising: athin-film transistor (TFT) backplane comprising: an insulator filmdisposed on a top surface of a substrate; a plurality of organic filmsdisposed on a top surface of the insulator film, the plurality oforganic films having different heights from the top surface of theinsulator film, each of the plurality of organic films being one among atransparent organic film, an opaque organic film, and a polymide; andpixel electrodes disposed on a top surface of each of the plurality oforganic films; and a plurality of LEDs respectively bonded to the pixelelectrodes disposed on the top surface of each of the plurality oforganic films, wherein the plurality of organic films has the differentheights according to a type of each of the plurality of LEDsrespectively bonded to the pixel electrodes disposed on the top surfaceof each of the plurality of organic films, wherein a thinnest LED amongthe plurality of LEDs is bonded to the pixel electrodes disposed on thetop surface of organic film having a lowest height among the pluralityof organic films, wherein an additional organic film is formed on anarea between the pixel electrodes disposed on the top surface of each ofthe plurality of organic films, the additional organic film having apredetermined height from the top surface of each of the plurality oforganic films, wherein the plurality of LEDs comprises a first type LED,a second type LED, and a third type LED, and wherein the first type LEDis thinner than either one or both of the second type LED and the thirdtype LED.
 2. The LED panel as claimed in claim 1, wherein the pluralityof LEDs respectively corresponds to a plurality of sub pixels includedin one pixel.
 3. The LED panel as claimed in claim 1, wherein theplurality of organic films is a black matrix.
 4. The LED panel asclaimed in claim 1, wherein the one organic film is disposed at apredetermined height between the pixel electrodes disposed on the oneorganic film.
 5. A light emitting diode (LED) panel comprising: athin-film transistor (TFT) backplane comprising: an insulator filmdisposed on a top surface of a substrate; a plurality of organic filmsdisposed on a top surface of the insulator film, the plurality oforganic films having different heights from a top surface of theinsulator film, each of the plurality of organic films being one among atransparent organic film, an opaque organic film, and a polymide; andpixel electrodes disposed on a top surface of each of the plurality oforganic films; and a plurality of LEDs respectively bonded to the pixelelectrodes disposed on the top surface of each of the plurality oforganic films, wherein the plurality of organic films has the differentheights according to a type of each of the plurality of LEDsrespectively bonded to the pixel electrodes disposed on the top surfaceof each of the plurality of organic films, wherein a thinnest LED amongthe plurality of LEDs is bonded to the pixel electrodes disposed on thetop surface of organic film having a lowest height among the pluralityof organic films, wherein an additional organic film is formed on anarea between the pixel electrodes disposed on the top surface of each ofthe plurality of organic films, the additional organic film having apredetermined height from the top surface of each of the plurality oforganic films, wherein the plurality of LEDs comprises a first type LED,a second type LED, and a third type LED, and wherein the first type LEDhas a smallest thickness among the plurality of LEDs.
 6. The LED panelas claimed in claim 5, wherein one LED having a smallest thickness amongthe plurality of LEDs is bonded to the pixel electrodes disposed on thetop surface of one organic film having a smallest height among theplurality of organic films.
 7. The LED panel as claimed in claim 5,wherein one among the plurality of organic films is disposed at apredetermined height between the pixel electrodes disposed on the oneamong the plurality of organic films.